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Guide to asphalt shingle roofing:

This article series explains how to identify & explain the most-common asphalt roof shingle failures and
how to obtain asphalt roofing shingle failure claims assistance. These defects occur on organic-mat or fiberglass-mat
asphalt roof shingles.

Common shingle failure factors include
improper storage and handling of the asphalt shingles before installation, improper nailing, improper flashing (which
pertains to any roofing material), and defective asphalt shingle product material leading to thermal splitting,
cracking, blistering, staining, and in some cases curling or cupping shingles.

"Organic felt" roof shingles refers to using cellulose (paper) as the substrate on which the shingle is constructed. The cardboard or cellulose shingle mat is impregnated with hot asphalt and coated with mineral granules to form a sunlight and weather resistant upper surface. Shown above: normal end-of-life curling at the edges of an organic shingle. This roof is fragile, should not be walked-on, and is ready for replacement. Below we describe other types of wear or damage found on this type of roof shingle.

Storm damage from wind and hail occur and need to be distinguished from defective asphalt shingle product or asphalt shingle installation errors.

By listing common causes of asphalt roof shingle failures and how to recognize them, building owners and roofing contractors may also be able to reduce the occurrence of asphalt roof shingle storage, handling, and installation errors that affect roof life. Readers are also invited contribute roof failure information to the web author for research purposes.

Mineral granule loss from asphalt roof shingles

This photograph shows severe loss of mineral granules from an asphalt shingle roof. This roof is way past
needing replacement and is almost certainly leaking. Even a roof with less dramatic granule loss is showing signs of wear
and reduced future life.
Anywhere that a shingle has lost the protection of its mineral granules that
shingle has a reduced life expectancy.

In all climates the loss of granules from an asphalt shingle or mineral-covered roll roofing roof means that area of the roof
shingle has lost its protection from sunlight. In freezing climates, shingle wear may accelerate in the area of lost granules
as the roof ages and is exposed to
freeze thaw cycles.

Once the shingle substrate is exposed by mineral granule loss, that area of the shingle will absorb
more water than its neighbors.
While in this photo the roof is "worn out",
there are several other conditions that can produce mineral loss on asphalt shingle roofs:

Cracking of old organic asphalt shingle roofs is a common, normal wear sign; roof wear accelerates as fine cracks (due to loss of volatiles in the asphalt and increasingly brittle shingles) permit water to enter the shingle substrate.
See ORGANIC FELT SHINGLE NORMAL WEAR

Granule loss on a new asphalt roof, loose mineral granules wash down the roof and will appear in gutters and at the ends of downspouts. This is
a normal condition unless it continues and begins to show black exposed roof shingle substrate.

Granule loss on roof shingles due to blister rash damage or wear: blistered asphalt shingles, normally an artifact of the manufacturing process, can be a point of wear due to foot traffic, hail damage, or aging and wear. If you see granule loss at the tops of shingle blisters this is probably what's going on on your roof. Details are
at BLISTERS on ASPHALT SHINGLES

Granule loss on a roof being walked-on: walking on any asphalt shingle roof loosens some of the mineral granules from their
attachment embedded in the asphalt used to impregnate and coat the shingle. If there is a lot of roof traffic, such as when work is
being done on a chimney, you may see "bald" areas of shingles with lost granules where people have been walking. This is damage
caused by workers and is not a product defect.

Granule loss on old asphalt shingle roofs: when an asphalt shingle roof is nearing the end of its life (or is at end of live as in the photo just above) we may see that granules
have begun to wash off of the shingles so as to leave large "bald" or nearly bald areas showing black shingle substrate. These shingles
have more porosity than those where their mineral granules remain in place and may already be leaking even if leaks are not quite visible
in the building interior. Such a roof is ready for replacement.
See GRANULE LOSS from SHINGLES

Granule loss on asphalt shingles due to storms: it is possible that severe weather, such as hailstorms, may damage shingles producing
pitting and granule loss. Such roofs have a reduced remaining life, depending on the severity of damage.
See HAIL DAMAGED SHINGLES
and
see WIND DAMAGE to ROOFS

Granule loss due to blistering: blisters or "pimple-like" protrusions from a shingle surface may be
a "cosmetic" manufacturing defect (at least in the opinion of the manufacturers). On at least some roofs we find that these blisters
ultimately become the first wear points on the shingle when their upper surface wears away (perhaps from foot traffic or weather) exposing
small round dots of missing granules on the shingle.
We discuss this defect and how to distinguish between defective shingle product and storm damage
at
ASPHALT SHINGLE BLISTERS,

Normal Age & Wear Cracking in Organic Mat Asphalt Roof Shingles

Organic mat asphalt shingles also may show cracking and accompanying granule loss. Defective asphalt shingle products of either organic or fiberglass based shingles may experience several failures including cracking, tearing, granule loss, blistering, etc. So, splits or cracks can occur in both organic-mat based and fiberglass-mat based asphalt roof shingles.

But thermal splitting is particularly a problem with fiberglass mat based asphalt roof shingles.

Normal Asphalt Single Wear Cracking & Granule Loss

Our photos (left and below) show a badly worn organic mat asphalt roof shingle with multiple fine cracks throughout its surface. This shingle is worn-out, but the wear pattern is homogenous over the roof slope and in our opinion is a normal wear condition.

Hairline cracks appear in the (generally thicker) organic mat based asphalt roof shingles as a normal sign of aging, and normally late in the life of the roof shingles.

Our OPINION is that a variegated cracking in a somewhat random pattern over the exposed shingle surface is a common age and wear indicator found on older organic based (paper) substrate asphalt shingle roofs.

Nevertheless, fine cracks through roof shingles, regardless of cause, mean accelerating wear rate and on a roof like the one shown at left, the roof needs replacement.

But catastrophic early shingle splitting failures like the ones illustrated earlier in this article were principally a problem of lightweight, fiberglass-mat based asphalt roof shingles made during the period discussed above. Roughly, from 1992 - 1997.

Readers are also invited contribute roof failure information to the web author for research purposes.
web author for research purposes.

Roof shingle fragility and damage risks

We recommend that inspectors stay off of cupped-asphalt shingle roofs, particularly in cold weather (shingles are more likely to break).

If
we absolutely have to walk on a cupped shingle roof, we would tiptoe carefully, avoiding stepping on the raised or cupped shingle
sections, or if doing repairs, we would prop a ladder up off of the roof surface and work from that scaffold as is sometimes done
with slate or other fragile roof surface repairs.

Is Roofing Felt Underlayment Needed Under Asphalt Roof Shingles?

While the requirement for felt underlayment beneath asphalt roof shingles seems to be a topic of almost timeless argument subject to much arm-waving and little reading of manufacturer's instructions and warranties, various sources recommend or require installation of a felt underlayment over the roof deck before asphalt roof shingles are installed.

The short answer is that underlayment should be installed beneath asphalt shingles.

Also see Choosing an Asphalt Shingle: Organic vs. Fiberglass, [PDF] Ted Cushman, The Journal of Light Construction, May 1993 for more about the debate around the advantages and disadvantages of organic mat asphalt shingles vs. fiberglass mat-based asphalt roof shingles.

Frequently Asked Questions (FAQs)

Try the search box below or CONTACT US by email if you cannot find the answer you need at InspectApedia.

Question:
can I replace individual organic roof shingles?

(Sept 4, 2012) hkorsh said:

can i replace organic shingles if i can find them

Reply:

HKorsh

Certainly; while fiberglass mat based roof shingles are very popular, organic mat (asphalt impregnated paper) are still made by some companies.

Watch out: for color mis-match or accept that new shingles may not exactly match older ones even if the product name and colour are the same as what was originally installed.

Question: my roof shingles are blistering and I want to make a warranty claim

Mike said:

I have asphalt shingles that were installed in 2000 on a new addition to my house. I just found out that my shingles are blistering and that they are asphalt which means they are defective. I have two extra shingles in my garage and they have a model 12020 on them but no name for the manufacturer. I have contacted the builder and awaiting a response about the brand of the shingles. Can you help me with finding out the brand name through the 12020 number on my shingles? I would like to file a claim. Thank you. Mike

Reply:

Mike,

First, the shingle manufacturers do not agree with you that blisters are shingle defect, arguing that they're of only cosmetic import. I do not completely agree as blisters can be a point of early granule loss.

Next, shingles do not develop blisters after installation - shingle blistering is an artifact that occurs during the much higher temperatures of fabrication.

IF you can demonstrate that the roof has failed (is leaking) before the end of its warranty period you may still have the basis for a warranty claim. But in my experience putting in a warranty claim on blisters alone is not likely to be fruitful. DO keep us posted - what you learn may assist other readers.

...

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Cupping Asphalt Shingle Explanation & Photos

Asphalt roof shingles often show cupping (a concave center), curling (raised edges which curl downwards), and fishmouthing
(raised edge of a shingle tab at its center with little curling). Each of these is discussed below.

This "normal" cupping or curling pattern will display shingles which are concave in their center,
with the corners and possibly the three exposed shingle tab edges curled such that the very edge of the shingle curls downwards.

Shingles in this condition are fragile and nearing end of life. In this condition, if someone walks on cupped shingles the raised
cupped sections will break and can lead to early failure and leaks.

Curling Asphalt Shingle Explanation & Photos

Curling roof shingles (see photos below) will show a curling-under at the edges of the shingle tab, first
at the lower edge and sometimes also at the two sides of the shingle tab.

In fact we have seen a "failed" roof that was not leaking until the fellow who was asked to inspect it
walked across this fragile surface.

From a ladder at the roof edge one could clearly see the virtual
footprints of broken shingle edges where the "inspector" had walked. It's best to stay off fragile roof
surfaces to avoid converting a "near end of life" condition to a "failed, leaking" condition.

Curling and cupping may occur together on the same roof, or shingles may appear to be curled-only
(or fishmouth-curled-only as you'll read next). We don't see cupping without some curling.

Fishmouthing Asphalt Shingle Explanation & Photos

You may not realize it but asphalt roof shingles are not quite waterproof and in particular the back side of asphalt
shingles is much less water resistant than the upper or exposed side.

The exposed side of an asphalt shingle
is protected from sun damage by a coating of mineral granules.

These shingles rely on the pitch of the roof
and mechanical drainage combined with proper placement or pattern of shingling on the roof to avoid leaks.
[Photo: Carl Gerosa]

Fishmouthed asphalt roof shingles:
An example of the less-waterproof back of asphalt roof shingles is seen below in our photo of "fishmouthed"
roof shingles. In these cases a specific "curling" pattern of shingles called "fishmouthing" is not simple age and wear.
This pattern displays a raised shingle edge (it's not cupped over at the very edge) which, if inspected closely,
will typically occur first and worst over the shingle butt joints where shingle sides abut one another.

Fishmouthed cupping of asphalt roof shingles is caused by excessive under-roof moisture such as by a poorly or un-vented attic or roof cavity.

Moisture escaping through the roof sheathing and up through the bottom of the shingles contacts the uppermost shingle which spans the butt
joint of shingles below, placing more moisture at that point on the shingle tab than elsewhere.
This uneven moisture, probably combined with weather exposure, leads to a raised, cupped "fishmouth" look on those shingles.

Laddering and stair-stepping of roof shingles

The photograph shows a sloppy "ladder pattern" installation of strip-type asphalt shingles. While opinions (and expertise) vary
among roofers, this ladder pattern shingle application may not be as durable a roof installation as one which staggered the shingle offsets more than a
single
six inches (or in this case only 3") left and right with each shingle course.

On other asphalt shingle roofs, particularly older ones,
you may notice that the pattern of fishmouth occurrence on an asphalt shingle roof follows a fairly regular or stair-stepped
pattern, or it may follow a regular "ladder" like pattern up the roof such as is shown in these photographs.

That's because the fishmouthing is occurring at
the butt joints of the shingles where more moisture is passing out of the roof structure into the back side of the shingle
above each butt joint.

You can thus determine the actual pattern in which the shingles were applied to the roof.

"Laddering," while
permitted by some manufacturers and standards, is a less workmanlike shingle installation and may result in a localized early
wear area on a roof. Ladder-pattern shingle application shows that the roofer liked to work up the roof from one position for
as long as possible before moving.

Like cupped and curled asphalt shingles, fishmouthed shingles are also fragile and near end of life and are, as with ordinary cupping, damaged if walked-on.

In some other cases a defective product might cup or curl But we don't have authoritative data on the frequency of that defect.
[Photo of fishmouthed shingles courtesy of Carl Gerosa, New Rochelle, NY.]

Workmanship: Fasteners/Nailing Problems lead to holes or wind blow-off. Notice that not only has
one shingle already fallen or been blown off of the roof, but its neighbors are sliding down. Diagnosis from a photograph is questionable but there appears to be a nailing problem here.

In discussing wind damage to roofing with your insurance adjuster or roofing contractor, be sure to review the details of
original and replacement shingle installation as this can give evidence about the underlying cause of roof failure as well
as informing you of how to avoid roof shingle blow-off in the future.

Slate Roofs, National Slate Association, 1926, reprinted 1977
by Vermont Structural Slate Co., Inc., Fair Haven, VT 05743, 802-265-4933/34. (We recommend this book if you can find it. It
has gone in and out of print on occasion.)

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